Thermoelectric diagnostic instrument

ABSTRACT

A thermoelectric diagnostic instrument including a housing, a thermocouple device in the housing and thermoconductor means for delivering heat and cold from the thermocouple device to contact elements located externally of the housing. Heat dissipating means including a heat sink for receiving excess heat from the thermocouple device and means for directing ambient air into engagement with the heat sink is also located in said housing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to diagnostic instruments and more particularlyto a thermoelectric instrument for applying heat and cold to smallselected portions of the patient's body. The device finds particularapplication as a dental pulp tester.

2. Description of the Prior Art

A diagnostic procedure often employed in dentistry is that of thermalpulp testing wherein the temperature of a tooth is either raised orlowered by the application of heat or cold. Conventionally used pulptesting procudures, such as those described in an article entitled"Thermal Pulp Testing" commencing on page 58 of the May/June, 1978 issueof General Dentistry magazine, are often inconvenient, time consuming,messy and potentially harmful to the patient. As a consequence, severalattempts have been made in the past to design instruments specificallyadapted for applying heat or cold to a localized area of the body suchas a tooth surface. Examples of such instruments are shown in thefollowing patents: Eidus U.S. Pat. No. 3,274,995 issued Sept. 27, 1966;Scher U.S. Pat. No. 3,533,397 issued Oct. 13, 1970; Crump et al U.S.Pat. No. 3,575,176 issued Apr. 20, 1971; Frank et al U..S. Pat. No.3,618,590 issued Nov. 9, 1971; and Foti U.S. Pat. No. 4,143,649 issuedMar. 13, 1979.

A major difficulty in the prior art, especially with respect to thosedevices employing mechanisms utilizing the Peltier effect, has been theefficient dissipation of excess heat build-up. The complex andvoluminous heat exchange systems and heat sinks thus far employed in anattempt to solve this problem has limited acceptance of such devices.

SUMMARY OF THE INVENTION

The purpose of the present invention is, therefore, to provide acompact, self contained diagnostic instrument for applying both heat andcold to localized areas which incorporates an efficient system fordissipating excess heat generated by a Peltier module employed therein.Several components of the device contribute to the attainment of thisobjective; in particular, the employment of insulated thermoconductorelements in operative association with the hot and cold junction platesof a Peltier device to deliver heat and cold to contact elementspositioned externally of a housing accommodating said Peltier device,heat sink means operatively associated with the hot junction plate ofsaid Peltier device, and a motor driven fan for drawing ambient air intothe interior of said housing into contact with the heat sink means andout of the housing.

Other features, advantages and objects of the present invention willbecome apparent with reference to the following detailed description andaccompanying drawings in which:

DESCRIPTION OF DRAWINGS

FIG. 1 is a side elevational sectional view of an instrument constructedaccording to the teachings of the present invention;

FIG. 2 is a sectional view taken along line 2--2 of FIG. 1;

FIG. 3 is an enlarged sectional view taken along line 3--3 of FIG. 1with portions thereof broken away;

FIG. 4 is an isometric view illustrating details of the thermoconductorelements and contact elements employed in the embodiment of FIG. 1; and

FIGS. 5 and 6 are side elevational views of alternative embodiments ofapparatus constructed in accordance with the teachings of the presentinvention.

DETAILED DESCRIPTION

A preferred form of apparatus constructed in accordance with theteachings of the present invention is shown in FIGS. 1-4, and includes ahousing 10 incorporating a cap member 12. Housing 10 additionallycomprises two threadedly engaged housing sections 14 and 16. The housingis preferably formed of plastic or other suitable insulating material.Cooperating flanges 18 and 20 at the ends of cap member 12 and section14, respectively, serve to secure the cap member to the rest of thehousing. The cap member may be readily removed from the rest of thehousing for cleaning, replacement, etc.

Disposed within the interior of the cap member of housing 10 isthermocouple device 22 utilizing the Peltier effect, said device 22being hereinafter referred to as the Peltier module. Peltier module 22includes opposed junction plates 24 and 26. When electrical current ispassed through the Peltier module the temperature of one of the platesis lowered and the temperature of the other is raised in a well knownmanner. In the disclosed arrangement, application of electrical energyto the Peltier module will result in plate 24 being heated and plate 26being cooled.

Disposed in face to face engagement with plates 24 and 26 arethermoconductor means in the form of thin, elongated strips 30 and 32 ofcopper or other suitable thermoconductive material which are preferablyembedded as shown in the insulating plastic material of cap member 12 sothat they are maintained in generally parallel relationship. At theoutermost extent of cap member 12, strips 30 and 32 are bent as shown toform curved contact elements 34 and 36 which extend outwardly from thecap member 12 in different directions whereby the contact elements arespaced from one another on opposite sides of the cap member. Contactelements 34 and 36 are preferably gold plated. It will be appreciatedthat upon actuation of Peltier module 22 heat will be transmitted tocontact element 34 by strip 30 and cold will be transmitted to contactelement 36 by strip 32. In FIG. 1 contact element 36 is shown in contactwith a tooth to impart cold thereto. With a simple twist of the wristthe hot contact element 34 alternatively may be placed in engagementwith a tooth. Suitable indicia is preferably provided on the contactelements themselves, or on the cap member, to indicate to the user whichcontact element is hot and which is cold. For example, red and blue dots40 and 42 could be applied to the cap member as shown to indicate thehot contact element and cold contact element, respectively.

Disposed adjacent to Peltier module 22 within the interior of housing 10is a heat sink 44 formed of aluminum or other suitable material. Strip30 extends beyond junction plate 24 and is positioned in engagement withthe heat sink 44 within a slot 46 formed therein as shown whereby excessheat generated by the Peltier module will be absorbed by the heat sinkand dissipated thereby. It should be noted that the cap member cannot beproperly affixed to the remainder of the housing unless strip 30 is inslot 46, thus insuring that the contact element 34 is always the heatedcontact element in conformance with the indication provided by indicia40.

Positioned adjacent to heat sink 44 is a thermostat 50, the function ofwhich will be described below. Adjacent to the thermostat 50 is anothercomponent of the heat dissipating mechanism of the present invention,namely, rotary fan 52 driven by electric motor 54. Upon actuation ofmotor 54 the fan 52 will serve to draw ambient air into the interior ofthe housing through air ingress apertures 60 formed in the housing aboutthe periphery thereof. The air will flow along a flow path indicated bythe arrows in FIG. 3. It will be noted that the flow path is partiallydefined by the heat sink and in particular by a groove 62 formed in theheat sink which provides communication between apertures 60 and spacedair flow passageways 64 formed in the heat sink. After passing throughthe heat sink the heated air passes fan 52 and proceeds along theinterior of housing 10 until it leaves the housing through air egressapertures 66 formed therein.

The Peltier module 22 and electric motor 54 are powered by batteries 70positioned within the housing interior. The batteries 70 are preferablyof a rechargeable type, such as nickel cadmium batteries, and chargerconnector pins 72 are provided to permit recharging of the device whenit is not in use. Suitable switch means 74 is provided to simultaneouslyestablish electrical communication between the batteries, motor 54 andPeltier module 22 through wiring 76. Thermostat 50 is positioned in theelectrical circuit so as to temporarily shut off power to the Peltiermodule when the heat of heat sink 44 passes a predetermined temperature.The motor 54 will continue to operate as long as switch means 74 isclosed however, if it is in parallel with the thermostat as ispreferred. FIG. 5 shows an alternative embodiment of the invention,differing from that previously described in that the Peltier module 22ais not removable with cap member 12a when the cap member is disconnectedfrom the rest of housing 10a. Such an arrangement is particularlydesirable for autoclaving. To assure correct alignment when the capmember is replaced with strips 30a and 32a in engagement with junctionplates 24a and 26a, respectively, suitable alignment means such as a keyand slot arrangement 82 and 84 are preferably employed.

FIG. 6 shows yet another alternative embodiment of the invention whereinthe instrument 90 has a socket accommodating a removable plug 92 whichis in turn connected by cord 94 to a transformer 96 adapted to beplugged into a conventional electrical socket.

I claim:
 1. A thermoelectric diagnostic instrument comprising:a housingdefining an interior; a thermocouple device mounted in said housing andhaving a plurality of junction plates; means for selectively inducing anelectrical current in said thermocouple device to actuate saidthermocouple device whereby at least one junction plate is cooled and atleast one junction plate is heated; separate thermoconductor elementsextending from each of said heated and cooled plates to separate contactelements being adapted for selective contact with a patient; and meansin said housing for dissipating excess heat generated by saidthermocouple device, said heat dissipating means comprising heat sinkmeans positioned in said housing interior and operatively connected tosaid heated plate and the thermoconductor element extending from saidheated plate.
 2. The instrument of claim 1 wherein said heat dissipatingmeans additionally comprises a motor driven fan in said housing interiorfor inducing an air flow within said housing interior along a flow pathbetween air ingress and air egress apertures formed in said housing toprovide air flow communication between the housing interior and theambient atmosphere, said flow path at least partially defined by apassageway in said heat sink means communicating with said air ingressapertures and directed toward said air egress apertures whereby ambientair heated by said heat sink means will be transported by said motordriven fan out of said air egress apertures and away from said heat sinkmeans and thermoconductor operatively associated therewith.
 3. Theinstrument of claim 1 wherein said thermoconductor elements comprise twoelongated thin thermoconductor elements and wherein said housingincludes a cap member formed of insulating material and releasablysecured to the rest of said housing, said thermoconductor elements beingpositioned within the cap member.
 4. The instrument of claim 3 whereinsaid contact elements are located at the ends of said thermoconductorelements remote from said thermocouple device and project outwardly fromsaid cap member on opposed sides of said cap member at the extremitythereof.
 5. The instrument of claim 1 wherein at least one of saidthermoconductor elements is in engagement with both the heat sink meansand a heated junction plate of said thermocouple device.
 6. Athermoelectric diagnostic instrument comprising:a housing defining aninterior; Peltier module means of unitary construction in said housingand having hot and cold junction plates; a thermoconductor element inoperative engagement with each of said plates for transmitting heat andcold to contact elements spaced from said plates and disposed externalof said housing; heat sink means positioned in said housing interior fordissipating heat generated by said Peltier module means and operativelyconnected to said hot plate and the thermoconductor element in operativeengagement with said hot plate to draw heat therefrom; and means in saidhousing interior for directing a flow of air past said heat sink meansand out of said housing.
 7. A thermoelectric diagnostic instrumentcomprising:a housing defining an interior and including a cap memberselectively removably connected to the rest of said housing; a Peltiermodule positioned in said housing interior and having hot and coldjunction plates; a heat sink; elongated thermoconductor elementspositioned in spaced relationship in said cap member and extending fromsaid Peltier module to a location remote therefrom, one of saidelongated thermoconductor elements being operatively connected to saidhot junction plate and said heat sink and the other of said elongatedthermoconductor elements being operatively connected to said coldjunction plate; and contact elements located at the ends of saidelongated thermoconductor elements remote from said Peltier module meansand projecting outwardly from said cap member at spaced locationsthereon.
 8. The instrument of claim 7 further comprising means forinducing an air flow within said housing interior along a flow paththrough said heat sink means.
 9. The instrument of claim 7 wherein saidcap member is constructed of heat insulating material and wherein saidthermoconductor elements comprise metallic strips imbedded in said capmember in spaced relationship to one another.
 10. The instrument ofclaim 7 wherein said contact elements are curved and at least partiallyformed from said metallic strips and extend outwardly from said capmember at the extremity thereof in opposite directions whereby thecontact elements are spaced from one another in opposition.
 11. Theinstrument of claim 7 additionally comprising alignment means forpositioning said cap member at a predetermined location relative to theremainder of said housing whereby said thermoconductor elements arealways disposed at a predetermined orientation relative to said housingand heat sink.
 12. The instrument of claim 11 additionally comprisingindicia on said instrument visible to the operator for identifying whichof said contact elements is heated and which is cooled by the elongatedthermoconductor elements.